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<h1 class="chapter" id="sec336">Chapter&#XA0;16&#XA0;&#XA0;The documentation generator (ocamldoc)</h1>
<ul>
<li><a href="ocamldoc.html#sec337">16.1&#XA0;&#XA0;Usage</a>
</li><li><a href="ocamldoc.html#sec349">16.2&#XA0;&#XA0;Syntax of documentation comments</a>
</li><li><a href="ocamldoc.html#sec364">16.3&#XA0;&#XA0;Custom generators</a>
</li><li><a href="ocamldoc.html#sec369">16.4&#XA0;&#XA0;Adding command line options</a>
</li></ul>
<p> <a id="c:ocamldoc"></a>

</p><p>This chapter describes OCamldoc, a tool that generates documentation from
special comments embedded in source files. The comments used by OCamldoc
are of the form <span class="c003">(**</span>&#X2026;<span class="c003">*)</span> and follow the format described
in section <a href="#s%3Aocamldoc-comments">16.2</a>.</p><p>OCamldoc can produce documentation in various formats: HTML, L<sup>A</sup>T<sub>E</sub>X,
TeXinfo, Unix man pages, and <span class="c003">dot</span> dependency graphs. Moreover,
users can add their own custom generators, as explained in
section <a href="#s%3Aocamldoc-custom-generators">16.3</a>.</p><p>In this chapter, we use the word <em>element</em> to refer to any of the
following parts of an OCaml source file: a type declaration, a value,
a module, an exception, a module type, a type constructor, a record
field, a class, a class type, a class method, a class value or a class
inheritance clause.</p>
<h2 class="section" id="sec337">16.1&#XA0;&#XA0;Usage</h2>
<p> <a id="s:ocamldoc-usage"></a></p>
<h3 class="subsection" id="sec338">16.1.1&#XA0;&#XA0;Invocation</h3>
<p>OCamldoc is invoked via the command <span class="c003">ocamldoc</span>, as follows:
</p><pre>
        ocamldoc <span class="c009">options sourcefiles</span>
</pre><h4 class="subsubsection" id="sec339">Options for choosing the output format</h4>
<p>The following options determine the format for the generated
documentation.</p><dl class="description"><dt class="dt-description">
<span class="c006">-html</span></dt><dd class="dd-description">
Generate documentation in HTML default format. The generated HTML pages
are stored in the current directory, or in the directory specified
with the <span class="c006">-d</span> option. You can customize the style of the
generated pages by editing the generated <span class="c003">style.css</span> file, or by providing
your own style sheet using option <span class="c003">-css-style</span>.
The file <span class="c003">style.css</span> is not generated if it already exists or if -css-style is used.</dd><dt class="dt-description"><span class="c006">-latex</span></dt><dd class="dd-description">
Generate documentation in L<sup>A</sup>T<sub>E</sub>X default format. The generated
L<sup>A</sup>T<sub>E</sub>X document is saved in file <span class="c003">ocamldoc.out</span>, or in the file
specified with the <span class="c006">-o</span> option. The document uses the style file
<span class="c003">ocamldoc.sty</span>. This file is generated when using the <span class="c003">-latex</span> option,
if it does not already exist.
You can change this file to customize the style of your L<sup>A</sup>T<sub>E</sub>X documentation.</dd><dt class="dt-description"><span class="c006">-texi</span></dt><dd class="dd-description">
Generate documentation in TeXinfo default format. The generated
L<sup>A</sup>T<sub>E</sub>X document is saved in file <span class="c003">ocamldoc.out</span>, or in the file
specified with the <span class="c006">-o</span> option.</dd><dt class="dt-description"><span class="c006">-man</span></dt><dd class="dd-description">
Generate documentation as a set of Unix <span class="c003">man</span> pages. The generated pages
are stored in the current directory, or in the directory specified
with the <span class="c006">-d</span> option.</dd><dt class="dt-description"><span class="c006">-dot</span></dt><dd class="dd-description">
Generate a dependency graph for the toplevel modules, in a format suitable
for displaying and processing by <span class="c003">dot</span>. The <span class="c003">dot</span> tool is available from
<a href="http://www.research.att.com/sw/tools/graphviz/"><span class="c003">http://www.research.att.com/sw/tools/graphviz/</span></a>.
The textual representation of the graph is written to the file
<span class="c003">ocamldoc.out</span>, or to the file specified with the <span class="c006">-o</span> option.
Use <span class="c003">dot ocamldoc.out</span> to display it.</dd><dt class="dt-description"><span class="c013"><span class="c003">-g</span> <span class="c009">file.cm[o,a,xs]</span></span></dt><dd class="dd-description">
Dynamically load the given file, which defines a custom documentation
generator. See section <a href="#s%3Aocamldoc-compilation-and-usage">16.4.1</a>. This
option is supported by the <span class="c003">ocamldoc</span> command (to load <span class="c003">.cmo</span> and <span class="c003">.cma</span> files)
and by its native-code version <span class="c003">ocamldoc.opt</span> (to load <span class="c003">.cmxs</span> files).
If the given file is a simple one and does not exist in
the current directory, then ocamldoc looks for it in the custom
generators default directory, and in the directories specified with
optional <span class="c003">-i</span> options.</dd><dt class="dt-description"><span class="c006">-customdir</span></dt><dd class="dd-description">
Display the custom generators default directory.</dd><dt class="dt-description"><span class="c013"><span class="c003">-i</span> <span class="c009">directory</span></span></dt><dd class="dd-description">
Add the given directory to the path where to look for custom generators.</dd></dl><h4 class="subsubsection" id="sec340">General options</h4>
<dl class="description"><dt class="dt-description"><span class="c013"><span class="c003">-d</span> <span class="c009">dir</span></span></dt><dd class="dd-description">
Generate files in directory <span class="c009">dir</span>, rather than the current directory.</dd><dt class="dt-description"><span class="c013"><span class="c003">-dump</span> <span class="c009">file</span></span></dt><dd class="dd-description">
Dump collected information into <span class="c009">file</span>. This information can be
read with the <span class="c003">-load</span> option in a subsequent invocation of <span class="c003">ocamldoc</span>.</dd><dt class="dt-description"><span class="c013"><span class="c003">-hide</span> <span class="c009">modules</span></span></dt><dd class="dd-description">
Hide the given complete module names in the generated documentation.
<span class="c009">modules</span> is a list of complete module names separated
by &#X2019;<span class="c003">,</span>&#X2019;, without blanks. For instance: <span class="c003">Pervasives,M2.M3</span>.</dd><dt class="dt-description"><span class="c006">-inv-merge-ml-mli</span></dt><dd class="dd-description">
Reverse the precedence of implementations and interfaces when merging.
All elements
in implementation files are kept, and the <span class="c006">-m</span> option
indicates which parts of the comments in interface files are merged
with the comments in implementation files.</dd><dt class="dt-description"><span class="c006">-keep-code</span></dt><dd class="dd-description">
Always keep the source code for values, methods and instance variables,
when available.</dd><dt class="dt-description"><span class="c013"><span class="c003">-load</span> <span class="c009">file</span></span></dt><dd class="dd-description">
Load information from <span class="c009">file</span>, which has been produced by
<span class="c003">ocamldoc -dump</span>. Several <span class="c003">-load</span> options can be given.</dd><dt class="dt-description"><span class="c013"><span class="c003">-m</span> <span class="c009">flags</span></span></dt><dd class="dd-description">
Specify merge options between interfaces and implementations.
(see section <a href="#s%3Aocamldoc-merge">16.1.2</a> for details).
<span class="c009">flags</span> can be one or several of the following characters:
<dl class="description"><dt class="dt-description">
<span class="c006">d</span></dt><dd class="dd-description"> merge description
</dd><dt class="dt-description"><span class="c006">a</span></dt><dd class="dd-description"> merge <span class="c003">@author</span>
</dd><dt class="dt-description"><span class="c006">v</span></dt><dd class="dd-description"> merge <span class="c003">@version</span>
</dd><dt class="dt-description"><span class="c006">l</span></dt><dd class="dd-description"> merge <span class="c003">@see</span>
</dd><dt class="dt-description"><span class="c006">s</span></dt><dd class="dd-description"> merge <span class="c003">@since</span>
</dd><dt class="dt-description"><span class="c006">b</span></dt><dd class="dd-description"> merge <span class="c003">@before</span>
</dd><dt class="dt-description"><span class="c006">o</span></dt><dd class="dd-description"> merge <span class="c003">@deprecated</span>
</dd><dt class="dt-description"><span class="c006">p</span></dt><dd class="dd-description"> merge <span class="c003">@param</span>
</dd><dt class="dt-description"><span class="c006">e</span></dt><dd class="dd-description"> merge <span class="c003">@raise</span>
</dd><dt class="dt-description"><span class="c006">r</span></dt><dd class="dd-description"> merge <span class="c003">@return</span>
</dd><dt class="dt-description"><span class="c006">A</span></dt><dd class="dd-description"> merge everything
</dd></dl></dd><dt class="dt-description"><span class="c006">-no-custom-tags</span></dt><dd class="dd-description">
Do not allow custom @-tags (see section <a href="#s%3Aocamldoc-tags">16.2.5</a>).</dd><dt class="dt-description"><span class="c006">-no-stop</span></dt><dd class="dd-description">
Keep elements placed after/between the <span class="c003">(**/**)</span> special comment(s)
(see section <a href="#s%3Aocamldoc-comments">16.2</a>).</dd><dt class="dt-description"><span class="c013"><span class="c003">-o</span> <span class="c009">file</span></span></dt><dd class="dd-description">
Output the generated documentation to <span class="c009">file</span> instead of <span class="c003">ocamldoc.out</span>.
This option is meaningful only in conjunction with the
<span class="c006">-latex</span>, <span class="c006">-texi</span>, or <span class="c006">-dot</span> options.</dd><dt class="dt-description"><span class="c013"><span class="c003">-pp</span> <span class="c009">command</span></span></dt><dd class="dd-description">
Pipe sources through preprocessor <span class="c009">command</span>.</dd><dt class="dt-description"><span class="c013"><span class="c003">-impl</span> <span class="c009">filename</span></span></dt><dd class="dd-description">
Process the file <span class="c009">filename</span> as an implementation file, even if its
extension is not <span class="c003">.ml</span>.</dd><dt class="dt-description"><span class="c013"><span class="c003">-intf</span> <span class="c009">filename</span></span></dt><dd class="dd-description">
Process the file <span class="c009">filename</span> as an interface file, even if its
extension is not <span class="c003">.mli</span>.</dd><dt class="dt-description"><span class="c013"><span class="c003">-text</span> <span class="c009">filename</span></span></dt><dd class="dd-description">
Process the file <span class="c009">filename</span> as a text file, even if its
extension is not <span class="c003">.txt</span>.</dd><dt class="dt-description"><span class="c006">-sort</span></dt><dd class="dd-description">
Sort the list of top-level modules before generating the documentation.</dd><dt class="dt-description"><span class="c006">-stars</span></dt><dd class="dd-description">
Remove blank characters until the first asterisk (&#X2019;<span class="c003">*</span>&#X2019;) in each
line of comments.</dd><dt class="dt-description"><span class="c013"><span class="c003">-t</span> <span class="c009">title</span></span></dt><dd class="dd-description">
Use <span class="c009">title</span> as the title for the generated documentation.</dd><dt class="dt-description"><span class="c013"><span class="c003">-intro</span> <span class="c009">file</span></span></dt><dd class="dd-description">
Use content of <span class="c009">file</span> as ocamldoc text to use as introduction (HTML,
L<sup>A</sup>T<sub>E</sub>X and TeXinfo only).
For HTML, the file is used to create the whole <span class="c003">index.html</span> file.</dd><dt class="dt-description"><span class="c006">-v</span></dt><dd class="dd-description">
Verbose mode. Display progress information.</dd><dt class="dt-description"><span class="c006">-version</span></dt><dd class="dd-description">
Print version string and exit.</dd><dt class="dt-description"><span class="c006">-vnum</span></dt><dd class="dd-description">
Print short version number and exit.</dd><dt class="dt-description"><span class="c006">-warn-error</span></dt><dd class="dd-description">
Treat Ocamldoc warnings as errors.</dd><dt class="dt-description"><span class="c006">-hide-warnings</span></dt><dd class="dd-description">
Do not print OCamldoc warnings.</dd><dt class="dt-description"><span class="c013"><span class="c003">-help</span> or <span class="c003">--help</span></span></dt><dd class="dd-description">
Display a short usage summary and exit.
</dd></dl><h4 class="subsubsection" id="sec341">Type-checking options</h4>
<p>OCamldoc calls the OCaml type-checker to obtain type
information. The following options impact the type-checking phase.
They have the same meaning as for the <span class="c003">ocamlc</span> and <span class="c003">ocamlopt</span> commands.</p><dl class="description"><dt class="dt-description"><span class="c013"><span class="c003">-I</span> <span class="c009">directory</span></span></dt><dd class="dd-description">
Add <span class="c009">directory</span> to the list of directories search for compiled
interface files (<span class="c003">.cmi</span> files).</dd><dt class="dt-description"><span class="c006">-nolabels</span></dt><dd class="dd-description">
Ignore non-optional labels in types.</dd><dt class="dt-description"><span class="c006">-rectypes</span></dt><dd class="dd-description">
Allow arbitrary recursive types. (See the <span class="c003">-rectypes</span> option to <span class="c003">ocamlc</span>.)</dd></dl><h4 class="subsubsection" id="sec342">Options for generating HTML pages</h4>
<p>The following options apply in conjunction with the <span class="c003">-html</span> option:</p><dl class="description"><dt class="dt-description">
<span class="c006">-all-params</span></dt><dd class="dd-description">
Display the complete list of parameters for functions and methods.</dd><dt class="dt-description"><span class="c013"><span class="c003">-charset</span> <span class="c009">charset</span></span></dt><dd class="dd-description">
Add information about character encoding being <span class="c009">charset</span>
(default is iso-8859-1).</dd><dt class="dt-description"><span class="c006">-colorize-code</span></dt><dd class="dd-description">
Colorize the OCaml code enclosed in <span class="c003">[ ]</span> and <span class="c003">{[ ]}</span>, using colors
to emphasize keywords, etc. If the code fragments are not
syntactically correct, no color is added.</dd><dt class="dt-description"><span class="c013"><span class="c003">-css-style</span> <span class="c009">filename</span></span></dt><dd class="dd-description">
Use <span class="c009">filename</span> as the Cascading Style Sheet file.</dd><dt class="dt-description"><span class="c006">-index-only</span></dt><dd class="dd-description">
Generate only index files.</dd><dt class="dt-description"><span class="c006">-short-functors</span></dt><dd class="dd-description">
Use a short form to display functors:
<pre>
module M : functor (A:Module) -&gt; functor (B:Module2) -&gt; sig .. end
</pre>
is displayed as:
<pre>
module M (A:Module) (B:Module2) : sig .. end
</pre></dd></dl><h4 class="subsubsection" id="sec343">Options for generating L<sup>A</sup>T<sub>E</sub>X files</h4>
<p>The following options apply in conjunction with the <span class="c003">-latex</span> option:</p><dl class="description"><dt class="dt-description">
<span class="c013"><span class="c003">-latex-value-prefix</span> <span class="c009">prefix</span></span></dt><dd class="dd-description">
Give a prefix to use for the labels of the values in the generated
L<sup>A</sup>T<sub>E</sub>X document.
The default prefix is the empty string. You can also use the options
<span class="c003">-latex-type-prefix</span>, <span class="c003">-latex-exception-prefix</span>,
<span class="c003">-latex-module-prefix</span>,
<span class="c003">-latex-module-type-prefix</span>, <span class="c003">-latex-class-prefix</span>,
<span class="c003">-latex-class-type-prefix</span>,
<span class="c003">-latex-attribute-prefix</span> and <span class="c003">-latex-method-prefix</span>.<p>These options are useful when you have, for example, a type and a value with
the same name. If you do not specify prefixes, L<sup>A</sup>T<sub>E</sub>X will complain about
multiply defined labels.</p></dd><dt class="dt-description"><span class="c013"><span class="c003">-latextitle</span> <span class="c009">n,style</span></span></dt><dd class="dd-description">
Associate style number <span class="c009">n</span> to the given L<sup>A</sup>T<sub>E</sub>X sectioning command
<span class="c009">style</span>, e.g. <span class="c003">section</span> or <span class="c003">subsection</span>. (L<sup>A</sup>T<sub>E</sub>X only.) This is
useful when including the generated document in another L<sup>A</sup>T<sub>E</sub>X document,
at a given sectioning level. The default association is 1 for <span class="c003">section</span>,
2 for <span class="c003">subsection</span>, 3 for <span class="c003">subsubsection</span>, 4 for <span class="c003">paragraph</span> and 5 for
<span class="c003">subparagraph</span>.</dd><dt class="dt-description"><span class="c006">-noheader</span></dt><dd class="dd-description">
Suppress header in generated documentation.</dd><dt class="dt-description"><span class="c006">-notoc</span></dt><dd class="dd-description">
Do not generate a table of contents.</dd><dt class="dt-description"><span class="c006">-notrailer</span></dt><dd class="dd-description">
Suppress trailer in generated documentation.</dd><dt class="dt-description"><span class="c006">-sepfiles</span></dt><dd class="dd-description">
Generate one <span class="c003">.tex</span> file per toplevel module, instead of the global
<span class="c003">ocamldoc.out</span> file.
</dd></dl><h4 class="subsubsection" id="sec344">Options for generating TeXinfo files</h4>
<p>The following options apply in conjunction with the <span class="c003">-texi</span> option:</p><dl class="description"><dt class="dt-description">
<span class="c006">-esc8</span></dt><dd class="dd-description">
Escape accented characters in Info files.</dd><dt class="dt-description"><span class="c006">-info-entry</span></dt><dd class="dd-description">
Specify Info directory entry.</dd><dt class="dt-description"><span class="c006">-info-section</span></dt><dd class="dd-description">
Specify section of Info directory.</dd><dt class="dt-description"><span class="c006">-noheader</span></dt><dd class="dd-description">
Suppress header in generated documentation.</dd><dt class="dt-description"><span class="c006">-noindex</span></dt><dd class="dd-description">
Do not build index for Info files.</dd><dt class="dt-description"><span class="c006">-notrailer</span></dt><dd class="dd-description">
Suppress trailer in generated documentation.
</dd></dl><h4 class="subsubsection" id="sec345">Options for generating <span class="c003">dot</span> graphs</h4>
<p>The following options apply in conjunction with the <span class="c003">-dot</span> option:</p><dl class="description"><dt class="dt-description">
<span class="c013"><span class="c003">-dot-colors</span> <span class="c009">colors</span></span></dt><dd class="dd-description">
Specify the colors to use in the generated <span class="c003">dot</span> code.
When generating module dependencies, <span class="c003">ocamldoc</span> uses different colors
for modules, depending on the directories in which they reside.
When generating types dependencies, <span class="c003">ocamldoc</span> uses different colors
for types, depending on the modules in which they are defined.
<span class="c009">colors</span> is a list of color names separated by &#X2019;<span class="c003">,</span>&#X2019;, as
in <span class="c003">Red,Blue,Green</span>. The available colors are the ones supported by
the <span class="c003">dot</span> tool.</dd><dt class="dt-description"><span class="c006">-dot-include-all</span></dt><dd class="dd-description">
Include all modules in the <span class="c003">dot</span> output, not only modules given
on the command line or loaded with the <span class="c006">-load</span> option.</dd><dt class="dt-description"><span class="c006">-dot-reduce</span></dt><dd class="dd-description">
Perform a transitive reduction of the dependency graph before
outputting the <span class="c003">dot</span> code. This can be useful if there are
a lot of transitive dependencies that clutter the graph.</dd><dt class="dt-description"><span class="c006">-dot-types</span></dt><dd class="dd-description">
Output <span class="c003">dot</span> code describing the type dependency graph instead of
the module dependency graph.
</dd></dl><h4 class="subsubsection" id="sec346">Options for generating man files</h4>
<p>The following options apply in conjunction with the <span class="c003">-man</span> option:</p><dl class="description"><dt class="dt-description">
<span class="c006">-man-mini</span></dt><dd class="dd-description">
Generate man pages only for modules, module types, classes and class
types, instead of pages for all elements.</dd><dt class="dt-description"><span class="c013"><span class="c003">-man-suffix</span> <span class="c009">suffix</span></span></dt><dd class="dd-description">
Set the suffix used for generated man filenames. Default is &#X2019;<span class="c003">3o</span>&#X2019;,
as in <span class="c003">List.3o</span>.</dd><dt class="dt-description"><span class="c013"><span class="c003">-man-section</span> <span class="c009">section</span></span></dt><dd class="dd-description">
Set the section number used for generated man filenames. Default is &#X2019;<span class="c003">3</span>&#X2019;.</dd></dl>
<h3 class="subsection" id="sec347">16.1.2&#XA0;&#XA0;Merging of module information</h3>
<p>
<a id="s:ocamldoc-merge"></a></p><p>Information on a module can be extracted either from the <span class="c003">.mli</span> or <span class="c003">.ml</span>
file, or both, depending on the files given on the command line.
When both <span class="c003">.mli</span> and <span class="c003">.ml</span> files are given for the same module,
information extracted from these files is merged according to the
following rules:
</p><ul class="itemize"><li class="li-itemize">
Only elements (values, types, classes, ...) declared in the <span class="c003">.mli</span>
file are kept. In other terms, definitions from the <span class="c003">.ml</span> file that are
not exported in the <span class="c003">.mli</span> file are not documented.
</li><li class="li-itemize">Descriptions of elements and descriptions in @-tags are handled
as follows. If a description for the same element or in the same
@-tag of the same element is present in both files, then the
description of the <span class="c003">.ml</span> file is concatenated to the one in the <span class="c003">.mli</span> file,
if the corresponding <span class="c003">-m</span> flag is given on the command line.
If a description is present in the <span class="c003">.ml</span> file and not in the
<span class="c003">.mli</span> file, the <span class="c003">.ml</span> description is kept.
In either case, all the information given in the <span class="c003">.mli</span> file is kept.
</li></ul>
<h3 class="subsection" id="sec348">16.1.3&#XA0;&#XA0;Coding rules</h3>
<p>
<a id="s:ocamldoc-rules"></a>
The following rules must be respected in order to avoid name clashes
resulting in cross-reference errors:
</p><ul class="itemize"><li class="li-itemize">
In a module, there must not be two modules, two module types or
a module and a module type with the same name.
In the default HTML generator, modules <span class="c003">ab</span> and <span class="c003">AB</span> will be printed
to the same file on case insensitive file systems.
</li><li class="li-itemize">In a module, there must not be two classes, two class types or
a class and a class type with the same name.
</li><li class="li-itemize">In a module, there must not be two values, two types, or two
exceptions with the same name.
</li><li class="li-itemize">Values defined in tuple, as in <span class="c003">let (x,y,z) = (1,2,3)</span>
are not kept by OCamldoc.
</li><li class="li-itemize">Avoid the following construction:
<pre>open Foo (* which has a module Bar with a value x *)
module Foo =
  struct
    module Bar =
      struct
        let x = 1
      end
  end
  let dummy = Bar.x
</pre>In this case, OCamldoc will associate <span class="c003">Bar.x</span> to the <span class="c003">x</span> of module
<span class="c003">Foo</span> defined just above, instead of to the <span class="c003">Bar.x</span> defined in the
opened module <span class="c003">Foo</span>.
</li></ul>
<h2 class="section" id="sec349">16.2&#XA0;&#XA0;Syntax of documentation comments</h2>
<p>
<a id="s:ocamldoc-comments"></a></p><p>Comments containing documentation material are called <em>special
comments</em> and are written between <span class="c003">(**</span> and <span class="c003">*)</span>. Special comments
must start exactly with <span class="c003">(**</span>. Comments beginning with <span class="c003">(</span> and more
than two <span class="c003">*</span> are ignored.</p>
<h3 class="subsection" id="sec350">16.2.1&#XA0;&#XA0;Placement of documentation comments</h3>
<p>
OCamldoc can associate comments to some elements of the language
encountered in the source files. The association is made according to
the locations of comments with respect to the language elements. The
locations of comments in <span class="c003">.mli</span> and <span class="c003">.ml</span> files are different.</p>
<h4 class="subsubsection" id="sec351">Comments in <span class="c003">.mli</span> files</h4>
<p>
A special comment is associated to an element if it is placed before or
after the element.<br>
A special comment before an element is associated to this element if&#XA0;:
</p><ul class="itemize"><li class="li-itemize">
There is no blank line or another special comment between the special
comment and the element. However, a regular comment can occur between
the special comment and the element.
</li><li class="li-itemize">The special comment is not already associated to the previous element.
</li><li class="li-itemize">The special comment is not the first one of a toplevel module.
</li></ul><p>A special comment after an element is associated to this element if
there is no blank line or comment between the special comment and the
element.</p><p>There are two exceptions: for constructors and record fields in
type definitions, the associated comment can only be placed after the
constructor or field definition, without blank lines or other comments
between them. The special comment for a constructor
with another constructor following must be placed before the &#X2019;<span class="c003">|</span>&#X2019;
character separating the two constructors.</p><p>The following sample interface file <span class="c003">foo.mli</span> illustrates the
placement rules for comments in <span class="c003">.mli</span> files.</p><pre>(** The first special comment of the file is the comment associated
    with the whole module.*)


(** Special comments can be placed between elements and are kept
    by the OCamldoc tool, but are not associated to any element.
    @-tags in these comments are ignored.*)

(*******************************************************************)
(** Comments like the one above, with more than two asterisks,
    are ignored. *)

(** The comment for function f. *)
val f : int -&gt; int -&gt; int
(** The continuation of the comment for function f. *)

(** Comment for exception My_exception, even with a simple comment
    between the special comment and the exception.*)
(* Hello, I'm a simple comment :-) *)
exception My_exception of (int -&gt; int) * int

(** Comment for type weather  *)
type weather =
| Rain of int (** The comment for constructor Rain *)
| Sun (** The comment for constructor Sun *)

(** Comment for type weather2  *)
type weather2 =
| Rain of int (** The comment for constructor Rain *)
| Sun (** The comment for constructor Sun *)
(** I can continue the comment for type weather2 here
  because there is already a comment associated to the last constructor.*)

(** The comment for type my_record *)
type my_record = {
    val foo : int ;    (** Comment for field foo *)
    val bar : string ; (** Comment for field bar *)
  }
  (** Continuation of comment for type my_record *)

(** Comment for foo *)
val foo : string
(** This comment is associated to foo and not to bar. *)
val bar : string
(** This comment is associated to bar. *)

(** The comment for class my_class *)
class my_class :
  object
    (** A comment to describe inheritance from cl *)
    inherit cl

    (** The comment for attribute tutu *)
    val mutable tutu : string

    (** The comment for attribute toto. *)
    val toto : int

    (** This comment is not attached to titi since
        there is a blank line before titi, but is kept
        as a comment in the class. *)

    val titi : string

    (** Comment for method toto *)
    method toto : string

    (** Comment for method m *)
    method m : float -&gt; int
  end

(** The comment for the class type my_class_type *)
class type my_class_type =
  object
    (** The comment for variable x. *)
    val mutable x : int

    (** The commend for method m. *)
    method m : int -&gt; int
end

(** The comment for module Foo *)
module Foo =
  struct
    (** The comment for x *)
    val x : int

    (** A special comment that is kept but not associated to any element *)
  end

(** The comment for module type my_module_type. *)
module type my_module_type =
  sig
    (** The comment for value x. *)
    val x : int

    (** The comment for module M. *)
    module M =
      struct
        (** The comment for value y. *)
        val y : int

        (* ... *)
      end

  end

</pre>
<h4 class="subsubsection" id="sec352">Comments in <span class="c003">.ml</span> files</h4>
<p>A special comment is associated to an element if it is placed before
the element and there is no blank line between the comment and the
element. Meanwhile, there can be a simple comment between the special
comment and the element. There are two exceptions, for
constructors and record fields in type definitions, whose associated
comment must be placed after the constructor or field definition,
without blank line between them. The special comment for a constructor
with another constructor following must be placed before the &#X2019;<span class="c003">|</span>&#X2019;
character separating the two constructors.</p><p>The following example of file <span class="c003">toto.ml</span> shows where to place comments
in a <span class="c003">.ml</span> file.</p><pre>(** The first special comment of the file is the comment associated
    to the whole module. *)

(** The comment for function f *)
let f x y = x + y

(** This comment is not attached to any element since there is another
    special comment just before the next element. *)

(** Comment for exception My_exception, even with a simple comment
    between the special comment and the exception.*)
(* A simple comment. *)
exception My_exception of (int -&gt; int) * int

(** Comment for type weather  *)
type weather =
| Rain of int (** The comment for constructor Rain *)
| Sun (** The comment for constructor Sun *)

(** The comment for type my_record *)
type my_record = {
    val foo : int ;    (** Comment for field foo *)
    val bar : string ; (** Comment for field bar *)
  }

(** The comment for class my_class *)
class my_class =
    object
      (** A comment to describe inheritance from cl *)
      inherit cl

      (** The comment for the instance variable tutu *)
      val mutable tutu = "tutu"
      (** The comment for toto *)
      val toto = 1
      val titi = "titi"
      (** Comment for method toto *)
      method toto = tutu ^ "!"
      (** Comment for method m *)
      method m (f : float) = 1
    end

(** The comment for class type my_class_type *)
class type my_class_type =
  object
    (** The comment for the instance variable x. *)
    val mutable x : int
    (** The commend for method m. *)
    method m : int -&gt; int
  end

(** The comment for module Foo *)
module Foo =
  struct
    (** The comment for x *)
    val x : int
    (** A special comment in the class, but not associated to any element. *)
  end

(** The comment for module type my_module_type. *)
module type my_module_type =
  sig
    (* Comment for value x. *)
    val x : int
    (* ... *)
  end
</pre>
<h3 class="subsection" id="sec353">16.2.2&#XA0;&#XA0;The Stop special comment</h3>
<p>
The special comment <span class="c003">(**/**)</span> tells OCamldoc to discard
elements placed after this comment, up to the end of the current
class, class type, module or module type, or up to the next stop comment.
For instance:
</p><pre>class type foo =
  object
    (** comment for method m *)
    method m : string

    (**/**)

    (** This method won't appear in the documentation *)
    method bar : int
  end

(** This value appears in the documentation, since the Stop special comment
    in the class does not affect the parent module of the class.*)
val foo : string

(**/**)
(** The value bar does not appear in the documentation.*)
val bar : string
(**/**)

(** The type t appears since in the documentation since the previous stop comment
toggled off the "no documentation mode". *)
type t = string
</pre><p>
The <span class="c006">-no-stop</span> option to <span class="c003">ocamldoc</span> causes the Stop special
comments to be ignored.</p>
<h3 class="subsection" id="sec354">16.2.3&#XA0;&#XA0;Syntax of documentation comments</h3>
<p>The inside of documentation comments <span class="c003">(**</span>&#X2026;<span class="c003">*)</span> consists of
free-form text with optional formatting annotations, followed by
optional <em>tags</em> giving more specific information about parameters,
version, authors, &#X2026; The tags are distinguished by a leading <span class="c003">@</span>
character. Thus, a documentation comment has the following shape:
</p><pre>(** The comment begins with a description, which is text formatted
   according to the rules described in the next section.
   The description continues until the first non-escaped '@' character.
   @author Mr Smith
   @param x description for parameter x
*)
</pre><p>Some elements support only a subset of all @-tags. Tags that are not
relevant to the documented element are simply ignored. For instance,
all tags are ignored when documenting type constructors, record
fields, and class inheritance clauses. Similarly, a <span class="c003">@param</span> tag on a
class instance variable is ignored.</p><p>At last, <span class="c003">(**)</span> is the empty documentation comment.</p>
<h3 class="subsection" id="sec355">16.2.4&#XA0;&#XA0;Text formatting</h3>
<p>Here is the BNF grammar for the simple markup language used to format
text descriptions.</p><table class="display dcenter"><tr class="c019"><td class="dcell"><table class="c001 cellpading0"><tr><td class="c018">
<a class="syntax" id="text"><span class="c010">text</span></a></td><td class="c015">::=</td><td class="c017">&#XA0;{<a class="syntax" href="#text-element"><span class="c010">text-element</span></a>}<sup>+</sup>
&#XA0;</td></tr>
<tr><td class="c018">&nbsp;</td></tr>
</table></td></tr>
</table><table class="c001 cellpading0"><tr><td class="c018">
<a class="syntax" id="text-element"><span class="c010">text-element</span></a></td><td class="c015">::=</td></tr>
</table><table class="c001 cellpading0"><tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{</span> { <span class="c004">0</span> &#X2026; <span class="c004">9</span> }<sup>+</sup> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">format <a class="syntax" href="#text"><span class="c010">text</span></a> as a section header;
the integer following <span class="c003">{</span> indicates the sectioning level. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{</span> { <span class="c004">0</span> &#X2026; <span class="c004">9</span> }<sup>+</sup> <span class="c004">:</span>  <span class="c010">label</span>  <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020"> same, but also associate the name <span class="c010">label</span> to the current point.
This point can be referenced by its fully-qualified label in a
<span class="c003">{!</span> command, just like any other element. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{b</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">set <a class="syntax" href="#text"><span class="c010">text</span></a> in bold. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{i</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">set <a class="syntax" href="#text"><span class="c010">text</span></a> in italic. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{e</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">emphasize <a class="syntax" href="#text"><span class="c010">text</span></a>. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{C</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">center <a class="syntax" href="#text"><span class="c010">text</span></a>. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{L</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">left align <a class="syntax" href="#text"><span class="c010">text</span></a>. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{R</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">right align <a class="syntax" href="#text"><span class="c010">text</span></a>. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{ul</span> <a class="syntax" href="#list"><span class="c010">list</span></a> <span class="c004">}</span> </td><td class="c020">build a list. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{ol</span> <a class="syntax" href="#list"><span class="c010">list</span></a> <span class="c004">}</span> </td><td class="c020">build an enumerated list. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c002"><span class="c003">{{:</span> <span class="c010">string</span> <span class="c003">}</span></span> &#XA0;<a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">put a link to the given address
(given as <span class="c010">string</span>) on the given <a class="syntax" href="#text"><span class="c010">text</span></a>. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c002"><span class="c003">[</span> <span class="c010">string</span> <span class="c003">]</span></span> </td><td class="c020">set the given <span class="c010">string</span> in source code style. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c002"><span class="c003">{[</span> <span class="c010">string</span> <span class="c003">]}</span></span> </td><td class="c020">set the given <span class="c010">string</span> in preformatted
				source code style.</td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c002"><span class="c003">{v</span> <span class="c010">string</span> <span class="c003">v}</span></span> </td><td class="c020">set the given <span class="c010">string</span> in verbatim style. </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c002"><span class="c003">{%</span> <span class="c010">string</span> <span class="c003">%}</span></span> </td><td class="c020">target-specific content
(L<sup>A</sup>T<sub>E</sub>X code by default, see details
in <a href="#sss%3Atarget-specific-syntax">16.2.4.4</a>) </td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c002"><span class="c003">{!</span> <span class="c010">string</span> <span class="c003">}</span></span> </td><td class="c020">insert a cross-reference to an element
(see section <a href="#sss%3Acrossref">16.2.4.2</a> for the syntax of cross-references).</td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{!modules:</span> <span class="c010">string</span> &#XA0;<span class="c010">string</span> ... <span class="c004">}</span> </td><td class="c020">insert an index table
for the given module names. Used in HTML only.</td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{!indexlist}</span> </td><td class="c020">insert a table of links to the various indexes
(types, values, modules, ...). Used in HTML only.</td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{^</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">set text in superscript.</td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"> <span class="c004">{_</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> </td><td class="c020">set text in subscript.</td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"><span class="c010">escaped-string</span></td><td class="c020">typeset the given string as is;
special characters (&#X2019;<span class="c003">{</span>&#X2019;, &#X2019;<span class="c003">}</span>&#X2019;, &#X2019;<span class="c003">[</span>&#X2019;, &#X2019;<span class="c003">]</span>&#X2019; and &#X2019;<span class="c003">@</span>&#X2019;)
must be	escaped by a &#X2019;<span class="c003">\</span>&#X2019;</td></tr>
<tr><td class="c024">&#X2223; </td><td class="c023"><span class="c010">blank-line</span></td><td class="c020">force a new line.
</td></tr>
</table><p> <br>

</p>
<h4 class="subsubsection" id="sec356">16.2.4.1&#XA0;&#XA0;List formatting</h4>
<table class="display dcenter"><tr class="c019"><td class="dcell"><table class="c001 cellpading0"><tr><td class="c018">
<a class="syntax" id="list"><span class="c010">list</span></a></td><td class="c015">::=</td><td class="c017">
&#XA0;</td></tr>
<tr><td class="c018">&nbsp;</td><td class="c015">&#X2223;</td><td class="c017">&#XA0;{&#XA0;<span class="c004">{-</span>&#XA0;<a class="syntax" href="#text"><span class="c010">text</span></a>&#XA0;<span class="c004">}</span>&#XA0;}<sup>+</sup>
&#XA0;</td></tr>
<tr><td class="c018">&nbsp;</td><td class="c015">&#X2223;</td><td class="c017">&#XA0;{&#XA0;<span class="c004">{li</span>&#XA0;<a class="syntax" href="#text"><span class="c010">text</span></a>&#XA0;<span class="c004">}</span>&#XA0;}<sup>+</sup>
</td></tr>
</table></td></tr>
</table><p>A shortcut syntax exists for lists and enumerated lists:
</p><pre>(** Here is a {b list}
- item 1
- item 2
- item 3

The list is ended by the blank line.*)
</pre><p>is equivalent to:
</p><pre>(** Here is a {b list}
{ul {- item 1}
{- item 2}
{- item 3}}
The list is ended by the blank line.*)
</pre><p>
The same shortcut is available for enumerated lists, using &#X2019;<span class="c003">+</span>&#X2019;
instead of &#X2019;<span class="c003">-</span>&#X2019;.
Note that only one list can be defined by this shortcut in nested lists.</p>
<h4 class="subsubsection" id="sec357">16.2.4.2&#XA0;&#XA0;Cross-reference formatting</h4>
<p>
<a id="sss:crossref"></a></p><p>Cross-references are fully qualified element names, as in the example
<span class="c003">{!Foo.Bar.t}</span>. This is an ambiguous reference as it may designate
a type name, a value name, a class name, etc. It is possible to make
explicit the intended syntactic class, using <span class="c003">{!type:Foo.Bar.t}</span> to
designate a type, and <span class="c003">{!val:Foo.Bar.t}</span> a value of the same name.</p><p>The list of possible syntactic class is as follows:
</p><div class="center">
<table class="c001 cellpading0"><tr><td class="c015"><span class="c003">tag</span></td><td class="c015">syntactic class</td></tr>
<tr><td class="hbar" colspan=2></td></tr>
<tr><td class="c018"><span class="c003">module:</span></td><td class="c017">module </td></tr>
<tr><td class="c018"><span class="c003">modtype:</span></td><td class="c017">module type </td></tr>
<tr><td class="c018"><span class="c003">class:</span></td><td class="c017">class </td></tr>
<tr><td class="c018"><span class="c003">classtype:</span></td><td class="c017">class type </td></tr>
<tr><td class="c018"><span class="c003">val:</span></td><td class="c017">value </td></tr>
<tr><td class="c018"><span class="c003">type:</span></td><td class="c017">type </td></tr>
<tr><td class="c018"><span class="c003">exception:</span></td><td class="c017">exception </td></tr>
<tr><td class="c018"><span class="c003">attribute:</span></td><td class="c017">attribute </td></tr>
<tr><td class="c018"><span class="c003">method:</span></td><td class="c017">class method </td></tr>
<tr><td class="c018"><span class="c003">section:</span></td><td class="c017">ocamldoc section </td></tr>
<tr><td class="c018"><span class="c003">const:</span></td><td class="c017">variant constructor </td></tr>
<tr><td class="c018"><span class="c003">recfield:</span></td><td class="c017">record field
</td></tr>
</table>
</div><p>In the case of variant constructors or record field, the constructor
or field name should be preceded by the name of the correspond type &#X2013;
to avoid the ambiguity of several types having the same constructor
names. For example, the constructor <span class="c003">Node</span> of the type <span class="c003">tree</span> will be
referenced as <span class="c003">{!tree.Node}</span> or <span class="c003">{!const:tree.Node}</span>, or possibly
<span class="c003">{!Mod1.Mod2.tree.Node}</span> from outside the module.</p>
<h4 class="subsubsection" id="sec358">16.2.4.3&#XA0;&#XA0;First sentence</h4>
<p>In the description of a value, type, exception, module, module type, class
or class type, the <em>first sentence</em> is sometimes used in indexes, or
when just a part of the description is needed. The first sentence
is composed of the first characters of the description, until
</p><ul class="itemize"><li class="li-itemize">
the first dot followed by a blank, or
</li><li class="li-itemize">the first blank line
</li></ul><p>
outside of the following text formatting :
 <span class="c004">{ul</span> <a class="syntax" href="#list"><span class="c010">list</span></a> <span class="c004">}</span> ,
 <span class="c004">{ol</span> <a class="syntax" href="#list"><span class="c010">list</span></a> <span class="c004">}</span> ,
 <span class="c002"><span class="c003">[</span> <span class="c010">string</span> <span class="c003">]</span></span> ,
 <span class="c002"><span class="c003">{[</span> <span class="c010">string</span> <span class="c003">]}</span></span> ,
 <span class="c002"><span class="c003">{v</span> <span class="c010">string</span> <span class="c003">v}</span></span> ,
 <span class="c002"><span class="c003">{%</span> <span class="c010">string</span> <span class="c003">%}</span></span> ,
 <span class="c002"><span class="c003">{!</span> <span class="c010">string</span> <span class="c003">}</span></span> ,
 <span class="c004">{^</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> ,
 <span class="c004">{_</span> <a class="syntax" href="#text"><span class="c010">text</span></a> <span class="c004">}</span> .</p>
<h4 class="subsubsection" id="sec359">16.2.4.4&#XA0;&#XA0;Target-specific formatting</h4>
<p>
<a id="sss:target-specific-syntax"></a></p><p>The content inside <span class="c003">{%foo: ... %}</span> is target-specific and will only be
interpreted by the backend <span class="c003">foo</span>, and ignored by the others. The
backends of the distribution are <span class="c003">latex</span>, <span class="c003">html</span>, <span class="c003">texi</span> and <span class="c003">man</span>. If
no target is specified (syntax <span class="c003">{% ... %}</span>), <span class="c003">latex</span> is chosen by
default. Custom generators may support their own target prefix.</p>
<h4 class="subsubsection" id="sec360">16.2.4.5&#XA0;&#XA0;Recognized HTML tags</h4>
<p>
The HTML tags <span class="c003">&lt;b&gt;..&lt;/b&gt;</span>,
<span class="c003">&lt;code&gt;..&lt;/code&gt;</span>,
<span class="c003">&lt;i&gt;..&lt;/i&gt;</span>,
<span class="c003">&lt;ul&gt;..&lt;/ul&gt;</span>,
<span class="c003">&lt;ol&gt;..&lt;/ol&gt;</span>,
<span class="c003">&lt;li&gt;..&lt;/li&gt;</span>,
<span class="c003">&lt;center&gt;..&lt;/center&gt;</span> and
<span class="c003">&lt;h[0-9]&gt;..&lt;/h[0-9]&gt;</span> can be used instead of, respectively,
 <span class="c004">{b ..}</span> ,
 <span class="c004">[..]</span> ,
 <span class="c004">{i ..}</span> ,
 <span class="c004">{ul ..}</span> ,
 <span class="c004">{ol ..}</span> ,
 <span class="c004">{li ..}</span> ,
 <span class="c004">{C ..}</span>  and
<span class="c003">{[0-9] ..}</span>.</p>
<h3 class="subsection" id="sec361">16.2.5&#XA0;&#XA0;Documentation tags (@-tags)</h3>
<p>
<a id="s:ocamldoc-tags"></a></p>
<h4 class="subsubsection" id="sec362">Predefined tags</h4>
<p>
The following table gives the list of predefined @-tags, with their
syntax and meaning.<br>

</p><table class="cellpadding1" border=1 style="border-spacing:0;"><tr><td class="c021"> <span class="c004">@author</span> <span class="c010">string</span> </td><td class="c021">The author of the element. One author per
<span class="c003">@author</span> tag.
There may be several <span class="c003">@author</span> tags for the same element. </td></tr>
<tr><td class="c021">
 <span class="c004">@deprecated</span> <a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">The <a class="syntax" href="#text"><span class="c010">text</span></a> should describe when the element was
deprecated, what to use as a replacement, and possibly the reason
for deprecation. </td></tr>
<tr><td class="c021">
 <span class="c004">@param</span> <span class="c010">id</span> &#XA0;<a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">Associate the given description (<a class="syntax" href="#text"><span class="c010">text</span></a>) to the
given parameter name <span class="c010">id</span>. This tag is used for functions,
methods, classes and functors. </td></tr>
<tr><td class="c021">
 <span class="c004">@raise</span> <span class="c010">Exc</span> &#XA0;<a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">Explain that the element may raise
the exception <span class="c010">Exc</span>. </td></tr>
<tr><td class="c021">
 <span class="c004">@return</span> <a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">Describe the return value and
its possible values. This tag is used for functions
and methods. </td></tr>
<tr><td class="c021">
 <span class="c002"><span class="c003">@see</span> <span class="c003">&lt;</span> <span class="c010">URL</span> <span class="c003">&gt;</span></span> &#XA0;<a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">Add a reference to the <span class="c010">URL</span>
with the given <a class="syntax" href="#text"><span class="c010">text</span></a> as comment. </td></tr>
<tr><td class="c021">
 <span class="c002"><span class="c003">@see</span> <span class="c003">'</span><span class="c010">filename</span><span class="c003">'</span></span> <a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">Add a reference to the given file name
(written between single quotes), with the given <a class="syntax" href="#text"><span class="c010">text</span></a> as comment. </td></tr>
<tr><td class="c021">
 <span class="c002"><span class="c003">@see</span> <span class="c003">"</span><span class="c010">document-name</span><span class="c003">"</span></span> <a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">Add a reference to the given
document name (written between double quotes), with the given <a class="syntax" href="#text"><span class="c010">text</span></a>
as comment. </td></tr>
<tr><td class="c021">
 <span class="c004">@since</span> <span class="c010">string</span> </td><td class="c021">Indicate when the element was introduced. </td></tr>
<tr><td class="c021">
 <span class="c004">@before</span>  <span class="c010">version</span>  <a class="syntax" href="#text"><span class="c010">text</span></a> </td><td class="c021">Associate the given description (<a class="syntax" href="#text"><span class="c010">text</span></a>)
to the given <span class="c010">version</span> in order to document compatibility issues. </td></tr>
<tr><td class="c021">
 <span class="c004">@version</span> <span class="c010">string</span> </td><td class="c021">The version number for the element. </td></tr>
</table>
<h4 class="subsubsection" id="sec363">Custom tags</h4>
<p>
<a id="s:ocamldoc-custom-tags"></a>
You can use custom tags in the documentation comments, but they will
have no effect if the generator used does not handle them. To use a
custom tag, for example <span class="c003">foo</span>, just put <span class="c003">@foo</span> with some text in your
comment, as in:
</p><pre>(** My comment to show you a custom tag.
@foo this is the text argument to the [foo] custom tag.
*)
</pre><p>
To handle custom tags, you need to define a custom generator,
as explained in section <a href="#s%3Aocamldoc-handling-custom-tags">16.3.2</a>.</p>
<h2 class="section" id="sec364">16.3&#XA0;&#XA0;Custom generators</h2>
<p>
<a id="s:ocamldoc-custom-generators"></a></p><p>OCamldoc operates in two steps:
</p><ol class="enumerate" type=1><li class="li-enumerate">
analysis of the source files;
</li><li class="li-enumerate">generation of documentation, through a documentation generator,
	which is an object of class <span class="c003">Odoc_args.class_generator</span>.
</li></ol><p>
Users can provide their own documentation generator to be used during
step 2 instead of the default generators.
All the information retrieved during the analysis step is available through
the <span class="c003">Odoc_info</span> module, which gives access to all the types and functions
representing the elements found in the given modules, with their associated
description.</p><p>The files you can use to define custom generators are installed in the
<span class="c003">ocamldoc</span> sub-directory of the OCaml standard library.</p>
<h3 class="subsection" id="sec365">16.3.1&#XA0;&#XA0;The generator modules</h3>
<p>
The type of a generator module depends on the kind of generated documentation.
Here is the list of generator module types, with the name of the generator
class in the module&#XA0;:
</p><ul class="itemize"><li class="li-itemize">
for HTML&#XA0;: <span class="c003">Odoc_html.Html_generator</span> (class <span class="c003">html</span>),
</li><li class="li-itemize">for L<sup>A</sup>T<sub>E</sub>X&#XA0;: <span class="c003">Odoc_latex.Latex_generator</span> (class <span class="c003">latex</span>),
</li><li class="li-itemize">for TeXinfo&#XA0;: <span class="c003">Odoc_texi.Texi_generator</span> (class <span class="c003">texi</span>),
</li><li class="li-itemize">for man pages&#XA0;: <span class="c003">Odoc_man.Man_generator</span> (class <span class="c003">man</span>),
</li><li class="li-itemize">for graphviz (dot)&#XA0;: <span class="c003">Odoc_dot.Dot_generator</span> (class <span class="c003">dot</span>),
</li><li class="li-itemize">for other kinds&#XA0;: <span class="c003">Odoc_gen.Base</span> (class <span class="c003">generator</span>).
</li></ul><p>
That is, to define a new generator, one must implement a module with
the expected signature, and with the given generator class, providing
the <span class="c003">generate</span> method as entry point to make the generator generates
documentation for a given list of modules&#XA0;:</p><pre>        method generate : Odoc_info.Module.t_module list -&gt; unit
</pre><p>
This method will be called with the list of analysed and possibly
merged <span class="c003">Odoc_info.t_module</span> structures.</p><p>It is recommended to inherit from the current generator of the same
kind as the one you want to define. Doing so, it is possible to
load various custom generators to combine improvements brought by each one.</p><p>This is done using first class modules (see chapter <a href="extn.html#s-first-class-modules">8.9</a>).</p><p>The easiest way to define a custom generator is the following this example,
here extending the current HTML generator. We don&#X2019;t have to know if this is
the original HTML generator defined in ocamldoc or if it has been extended
already by a previously loaded custom generator&#XA0;:</p><pre>module Generator (G : Odoc_html.Html_generator) =
struct
  class html =
    object(self)
      inherit G.html as html
      (* ... *)

      method generate module_list =
        (* ... *)
        ()

      (* ... *)
  end
end;;

let _ = Odoc_args.extend_html_generator (module Generator : Odoc_gen.Html_functor);;
</pre><p>
To know which methods to override and/or which methods are available,
have a look at the different base implementations, depending on the
kind of generator you are extending&#XA0;:

</p><ul class="itemize"><li class="li-itemize">
for HTML&#XA0;: <a href="https://github.com/ocaml/ocaml/blob/4.06/ocamldoc/odoc_html.ml"><span class="c003">odoc_html.ml</span></a>,
</li><li class="li-itemize">for L<sup>A</sup>T<sub>E</sub>X&#XA0;: <a href="https://github.com/ocaml/ocaml/blob/4.06/ocamldoc/odoc_latex.ml"><span class="c003">odoc_latex.ml</span></a>,
</li><li class="li-itemize">for TeXinfo&#XA0;: <a href="https://github.com/ocaml/ocaml/blob/4.06/ocamldoc/odoc_texi.ml"><span class="c003">odoc_texi.ml</span></a>,
</li><li class="li-itemize">for man pages&#XA0;: <a href="https://github.com/ocaml/ocaml/blob/4.06/ocamldoc/odoc_man.ml"><span class="c003">odoc_man.ml</span></a>,
</li><li class="li-itemize">for graphviz (dot)&#XA0;: <a href="https://github.com/ocaml/ocaml/blob/4.06/ocamldoc/odoc_dot.ml"><span class="c003">odoc_dot.ml</span></a>.
</li></ul>
<h3 class="subsection" id="sec366">16.3.2&#XA0;&#XA0;Handling custom tags</h3>
<p>
<a id="s:ocamldoc-handling-custom-tags"></a></p><p>Making a custom generator handle custom tags (see
<a href="#s%3Aocamldoc-custom-tags">16.2.5</a>) is very simple.</p><h4 class="subsubsection" id="sec367">For HTML</h4>
<p>
Here is how to develop a HTML generator handling your custom tags.</p><p>The class <span class="c003">Odoc_html.Generator.html</span> inherits
from the class <span class="c003">Odoc_html.info</span>, containing a field <span class="c003">tag_functions</span> which is a
list pairs composed of a custom tag (e.g. <span class="c003">"foo"</span>) and a function taking
a <span class="c003">text</span> and returning HTML code (of type <span class="c003">string</span>).
To handle a new tag <span class="c003">bar</span>, extend the current HTML generator
and complete the <span class="c003">tag_functions</span> field:
</p><pre>module Generator (G : Odoc_html.Html_generator) =
struct
  class html =
    object(self)
      inherit G.html

      (** Return HTML code for the given text of a bar tag. *)
      method html_of_bar t = (* your code here *)

      initializer
        tag_functions &lt;- ("bar", self#html_of_bar) :: tag_functions
  end
end
let _ = Odoc_args.extend_html_generator (module Generator : Odoc_gen.Html_functor);;
</pre><p>
Another method of the class <span class="c003">Odoc_html.info</span> will look for the
function associated to a custom tag and apply it to the text given to
the tag. If no function is associated to a custom tag, then the method
prints a warning message on <span class="c003">stderr</span>.</p>
<h4 class="subsubsection" id="sec368">For other generators</h4>
<p>
You can act the same way for other kinds of generators.</p>
<h2 class="section" id="sec369">16.4&#XA0;&#XA0;Adding command line options</h2>
<p>
The command line analysis is performed after loading the module containing the
documentation generator, thus allowing command line options to be added to the
list of existing ones. Adding an option can be done with the function
</p><pre>        Odoc_args.add_option : string * Arg.spec * string -&gt; unit
</pre><p>Note: Existing command line options can be redefined using
this function.</p>
<h3 class="subsection" id="sec370">16.4.1&#XA0;&#XA0;Compilation and usage</h3>
<p>
<a id="s:ocamldoc-compilation-and-usage"></a></p>
<h4 class="subsubsection" id="sec371">Defining a custom generator class in one file</h4>
<p>
Let <span class="c003">custom.ml</span> be the file defining a new generator class.
Compilation of <span class="c003">custom.ml</span> can be performed by the following command&#XA0;:
</p><pre>
        ocamlc -I +ocamldoc -c custom.ml
</pre><p>
The file <span class="c003">custom.cmo</span> is created and can be used this way&#XA0;:
</p><pre>
        ocamldoc -g custom.cmo <span class="c009">other-options source-files</span>
</pre><p>
Options selecting a built-in generator to <span class="c003">ocamldoc</span>, such as
<span class="c003">-html</span>, have no effect if a custom generator of the same kind is provided using
<span class="c003">-g</span>. If the kinds do not match, the selected built-in generator is used and the
custom one is ignored.</p>
<h4 class="subsubsection" id="sec372">Defining a custom generator class in several files</h4>
<p>
It is possible to define a generator class in several modules, which
are defined in several files <span class="c009">file</span><sub>1</sub><span class="c003">.ml</span>[<span class="c003">i</span>],
<span class="c009">file</span><sub>2</sub><span class="c003">.ml</span>[<span class="c003">i</span>], ..., <span class="c009">file</span><sub><span class="c009">n</span></sub><span class="c003">.ml</span>[<span class="c003">i</span>]. A <span class="c003">.cma</span>
library file must be created, including all these files.</p><p>The following commands create the <span class="c003">custom.cma</span> file from files
<span class="c009">file</span><sub>1</sub><span class="c003">.ml</span>[<span class="c003">i</span>], ..., <span class="c009">file</span><sub><span class="c009">n</span></sub><span class="c003">.ml</span>[<span class="c003">i</span>]&#XA0;:
</p><pre>
ocamlc -I +ocamldoc -c <span class="c009">file</span><sub>1</sub>.ml[i]
ocamlc -I +ocamldoc -c <span class="c009">file</span><sub>2</sub>.ml[i]
...
ocamlc -I +ocamldoc -c <span class="c009">file</span><sub><span class="c009">n</span></sub>.ml[i]
ocamlc -o custom.cma -a <span class="c009">file</span><sub>1</sub>.cmo <span class="c009">file</span><sub>2</sub>.cmo ... <span class="c009">file</span><sub><span class="c009">n</span></sub>.cmo
</pre><p>
Then, the following command uses <span class="c003">custom.cma</span> as custom generator:
</p><pre>
        ocamldoc -g custom.cma <span class="c009">other-options source-files</span>
</pre>
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